Wireless communication standards continue to evolve. For example, in the cellular context, standards are currently evolving from third generation (3G) standards to fourth generation (4G) standards. The 3G standards include GSM and UMTS standards promulgated by an organization known as the 3G Partnership Project (3GPP) and CDMA2000 standards such as High Rate Packet Data (HRPD) promulgated by an organization referred to as 3GPP2. The 4G standards currently under development by 3GPP are generally referred to as Long Term Evolution (LTE) standards. The 3GPP and 3GPP2 specification documents, including, for example, 3GPP2 Specification No. A.S0008-0 v4.0, “Interoperability Specification (IOS) for High Rate Packet Data (HRPD) Radio Access Network Interfaces with Session Control in the Access Network,” May 2007, are freely available online and are incorporated by reference herein in their entirety.
LTE networks will make use of an Internet protocol (IP) based packet core referred to as Evolved Packet Core (EPC). In order to facilitate the transition to LTE networks, 3GPP2 has developed what is referred to as enhanced HRPD (eHRPD), which allows HRPD access networks to utilize the LTE EPC. Such HRPD access networks are also referred to herein as eHRPD access networks.
The eHRPD approach utilizes an HRPD Serving Gateway (HSGW) to interface eHRPD access networks to the LTE EPC. The HSGW provides interworking between the eHRPD access networks and a Packet Data Network (PDN) of the EPC. For example, the HSGW may interface with a PDN gateway (PGW) of the EPC. The HSGW may be implemented as a separate network element, or alternatively may be viewed as comprising or being incorporated into a Packet Data Serving Node (PDSN) in the access network.
The 3GPP LTE standards generally require the use of a specially-formatted authentication protocol when allowing access to the EPC from a non-3GPP system such as an eHRPD access network. This authentication protocol is carried out between a mobile station or other user equipment associated with the non-3GPP system element and an authentication server of the EPC using an authenticator that in the eHRPD context typically comprises the HSGW. The authentication protocol generally involves key derivation in which keying material is bound to appropriate context information such as Mobile Station Identity (MSID) and authenticator identity.
In conventional practice, the authenticator identity may be given, for example, by a carrier identifier, such as a combination of Mobile Country Code (MCC) and Mobile Network Code (MNC). Other types of information may be used to represent the authenticator identity to both the user equipment and the authentication server. Such information may simply identify the particular technology used by the authenticator, e.g., HRPD.